1. Field of the Invention
The present invention relates to a process for the selective extraction and ultimate recovery of copper from an acidic chloride solution containing copper, and more particularly to a process for selectively extracting and ultimately recovering copper from both a spent cupric chloride etch and a spent ammoniacal etch, both of which are derived from etching copper from printed circuit boards in the electronic industry.
2. Description of the Prior Art
Selective recovery of copper from solutions containing the same has become a major concern of the metals industry in recent years. Solvent extraction is one technique for recovering copper from solutions which has achieved increasing popularity and acceptance, in particular, liquid-liquid type solvent extraction. Liquid-liquid solvent extraction involves contacting a copper-containing, aqueous feed solution with an organic extractant. The organic extractant has an active organic extractant for selectively extracting copper dissolved in an inert organic solvent (carrier), such as kerosene. Hydroxy oximes, beta diketones and tertiary amines are examples of active, selective organic extractants. Multistage liquid-liquid extraction may be employed to achieve substantially complete extraction of copper from a solution containing copper. The copper-containing aqueous feed solution and the organic extractant flow countercurrently between the extraction stages. In each stage, the active organic extractant selectively extracts copper from the solution containing the same, resulting in a copper loaded organic phase and a raffinate from which copper has been removed. Each stage constitutes a mixer-settler system wherein the aqueous feed and organic extractant are mixed for a period of time and then permitted to settle so as to separate the phases. The copper from the loaded organic extractant is selectively stripped therefrom by contact with a suitable stripping solution.
Several patents relate to processes which involve, at least in part, the use of liquid-liquid extraction to selectively recover copper. Examples of such patents are U.S. Pat. No. 3,224,873 issued to Swanson on Dec. 21, 1965, U.S. Pat. No. 3,761,249 issued to Ritcey et al on Sept. 25, 1973, U.S. Pat. No. 3,849,269 issued to Hartwig et al on Nov. 19, 1974, U.S. Pat. No. 3,853,981 issued to Hadzeriga on Dec. 10, 1974, U.S. Pat. No. 3,855,090 issued to Skarbo on Dec. 17, 1974, U.S. Pat. No. 3,872,209 issued to Hazen et al on Mar. 18, 1975, U.S. Pat. No. 3,887,679 issued to Wegstol et al on June 3, 1975, U.S. Pat. No. 3,907,966 issued to Skarbo on Sept. 23, 1975, U.S. Pat. No. 3,927,169 issued to Goren et al on Dec. 16, 1975, U.S. Pat. No. 3,950,487 issued to Pemsler et al on Apr. 13, 1976, U.S. Pat. No. 3,971,652 issued to Bryson on July 27, 1976, U.S. Pat. No. 3,981,966 issued to Baucom on Sept. 21, 1976, U.S. Pat. No. 3,988,151 issued to Skarbo on Oct. 26, 1976, U.S. Pat. No. 4,023,964 issued to DeMarthe et al on May 17, 1977, U.S. Pat. No. 4,036,639 issued to Yarko on July 19, 1977 and German Pat. No. 26 15 287 issued to Perschke et al on Oct. 6, 1977.
As copper reserves dwindle under increased copper demand, and therefore exploitation, it has become imperative to recycle "waste" copper. One source of such "waste" copper is copper contained in spent etches derived from the etching of copper from printed electronic circuit boards. Conventionally, aqueous solutions of hydrochloric acid and sodium chlorate or aqueous solutions of ammonia and ammonium chloride are employed to etch copper from printed electronic circuit boards. The resultant spent etch solution contains relatively large quantities of copper in solution. Currently, these spent etch solutions are waste streams in the electronic industry, and in fact, many firms pay other concerns to properly dispose the spent etch solutions.
U.S. Pat. No. 3,440,036 issued to Spinney on Apr. 22, 1969 relates to a process for liquid-liquid ion exchange extraction of copper from a ammonium sulfate-ammonium peroxy-disulfate etch solution with hydroxy oximes as the extraction agent. The pH of the etch solution must range from about 5.5 to about 7.5 when utilizing a hydroxy oxime to effectively extract copper therefrom. U.S. Pat. No. 4,083,758 issued to Hamby et al on Apr. 1, 1978 discloses a process for recovering copper values from a solution containing such values along with chloride ions, particularly spent, ammoniacal etching solutions derived from the manufacture of printed electronic circuit boards. The process comprises removing copper from the solution utilizing conventional liquid-liquid extraction techniques employing a LIX reagent, organic extractants manufactured by Henkel Corporation, in an organic vehicle as the extractant. The copper values are thereafter stripped from the extractant by contacting the extractant with a strong sulfuric acid solution as conventionally known. An electrowinning circuit is provided to recover "wire-grade" metallic copper from the acidic stripping solution.
These processes do not provide for product selectivity from diverse copper-containing feed streams and, therefore, have limited marketability. Nor do these processes encompass a plurality of diverse feed streams which may be concurrently processed thereby. Thus, it can be appreciated that a need exists for an improved process for selectively extracting copper from solution(s) containing the same.